-LRB- CNN -RRB- -- What on Earth would drive a man to swim in Arctic waters wearing nothing but Speedos , goggles and a cap ?

Lewis Pugh braves the icy water off the arctic archipelogo of Svalbard .

For Lewis Pugh , it was a love of the environment and a passionate desire to save the Arctic from global warming .

His 1 km swim -LRB- 0.62 of a mile -RRB- in 2007 made him the first person to complete a long-distance swim at the North Pole -- the purpose , to highlight the fact that it was possible to swim for a kilometer in a place that should be solid ice .

Pugh , now aged 39 , is a former maritime lawyer who abandoned his practice six years ago to become a full-time environmentalist and adventurer .

Since then he has become the first person to complete long-distance swims in all five of the world 's oceans and has become the world 's leading cold water swimmer .

Born in England and brought up in South Africa , Pugh sees himself in the mould of pioneering adventurers like Sir Edmund Hillary , fearlessly braving waters no one else would dare swim . But rather than just aiming for a place in the history books , his motivation is to publicize the environmental damage he has witnessed on his swims .

In 2006 , to raise awareness about global warming and that year 's drought in England , Pugh swam the entire length of the River Thames -- all except the first 26 miles , which had already dried up . He took a break from the 200-mile journey to call in at No. 10 Downing Street , where he discussed climate change with Tony Blair .

The next year , Pugh became the first person to swim the 87 mile-width of the Maldives . The 10-day swim was Pugh 's way of raising awareness of how climate change is threatening to submerge low-lying islands .

But he is best known for his North Pole adventure . His Arctic swim lasted 19 minutes in temperatures of around minus 2 degrees Celsius . Were any normal person to fall into waters that cold they would be in serious trouble .

Pugh 's long-time coach Professor Tim Noakes told CNN , `` People usually drown very quickly on exposure to cold water because they start to hyperventilate and when you hyperventilate you ca n't coordinate . They inhale water and they ca n't coordinate their swimming . Most people ca n't even go 20 meters if they are exposed to ice-cold water . ''

But Pugh has developed a unique mechanism for overcoming freezing conditions . He is apparently able to increase his body temperature by will power alone . In a process that Noakes has dubbed `` anticipatory thermogenesis '' , Pugh can raise his body temperature to a feverish 38.4 C , some 1.5 degrees above normal body temperature .

Noakes first noted this extraordinary ability during a training session . Before entering the water , Pugh cast his mind back to a traumatic parachuting accident he witnessed when he was a soldier in the British army , reliving the event in detail . Noakes recorded an increase in Pugh 's body temperature and over the next fortnight , as Pugh was exposed to more cold-water swims , he was able to increase his temperature even further , peaking at 38.4 C .

These days , before Pugh braves sub-zero waters he listens to U.S.rapper Eminem , gets himself into an aggressive state of mind and drives up his internal temperature . Once he hits the water , it 's all about mental strength .

Noakes told CNN `` The moment you dive into cold water your temperature drops and the brain sends a message to get out of the water . The first thing Pugh has to do is control that response . What happens is that I become his brain , so he says ` fine , as long as Dr Noakes allows me to swim , it 's safe and I must just ignore what my brain is telling me . ' ''

Achieving that level of willpower does n't come easily . While Pugh does an hour of cold-water swimming a day , he devotes four hours a day to mind training . His technique is to visualize his swim from beginning to end .

`` I can taste salt water in my mouth . I can hear the sounds of the engines , of Tim Noakes screaming at me . I can feel ice burning my skin , I can smell the sea air . I absolutely live that moment . I have swum the North Pole hundreds of times in my mind , '' he told CNN .

If the Arctic swim was intended to highlight shrinking polar ice caps , Pugh acknowledges that there 's still plenty of work to do on that front and he now speaks on environmental issues all over the world .

In 2008 Pugh founded the Polar Defense Project with the aim of protecting the Arctic and of encouraging world leaders to take action to stop climate change . As well the risk of polar melting , Pugh sees an Arctic treaty as essential to prevent the exploitation of the North Pole for oil and gas .

As Pugh put it after completing his Arctic swim , `` I 'm relieved that it 's over . Now the real work begins . ''

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Lewis Pugh was the first man to complete a long-distance swim in the Arctic

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`` Most people ca n't go 20 meters in ice-cold water , '' says his coach

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Pugh is able to increase his body temperature using will power alone

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His extreme swims are intended to publicize the effects of global warming